The present invention generally relates to fabrication methods and the resulting structures for semiconductor devices. More specifically, the present invention relates to the structure and formation of different sized solder bumps for signal carrying and solder bumps for ground plane and/or mechanical connections.
Generally, semiconductor devices utilize metal die pads for receiving and supplying signals to and from other circuitry. The die pad is usually in a rectangular shape, wherein some of the metal layers are utilized for carrying signals between the die pads and other circuitry of the IC chip. The other die pads are used for mechanical connections and/or ground connections. One method of die assembly utilizes a solder bumped die that are flip chip assembled onto a workpiece. Flip chip interconnections provide short electrical connecting paths as compared to wire bonds, and therefore better electrical performance including speed. Conventional semiconductor dies for flip chip applications typically have a single bump size including a single bump height and a single bump diameter that that are formed over die pads of a single fixed size. Other semiconductor dies vary the bump size but alter the height of the receiving pad to compensate for bump size variation.